Blender to Unreal Engine tips

Software:
Blender 2.9 | Unreal Engine 4.25

The following is a list of guidelines for preparation and export of 3D content from Blender to Unreal Engine 4 via the FBX file format.

Disclaimer:
This is not a formal specification.
It’s a list of tips I found to work well in my own experience.
* Some of the issues listed here may have already been solved


Blender Scene and model settings:

System units in Blender:
Define the scene units in Blender as:
Metric unit with 0.01 scale (centimeters)
And model your content correctly using centimeter units.
* Modeling in 1 meter units may seem to be imported correctly into UE4 but will cause unsolvable problems like a skeletal mesh physics asset having incorrect auto-generated shapes, a problem that in my experience can’t be fixed manually.

Transform:
Model your model in Blender facing the -Y world axis, +Z obviously being up (obviously for Blender).
* This way the model is aligned to Blender’s views so the front view displays the model’s front etc.
Make sure to apply your model’s transformations before export.

Armatures:
Make sure the Armature object isn’t named “Armature”.
naming or leaving the Blender skeleton named “Armature” will cause the UE4 importer to fail due to “multiple roots”.
* Also remember some weird related bug with animation scale incorrectly imported, but can’t confirm this now..
No need for a dedicated root bone in the hierarchy. the Armature object is the root of the bone hierarchy.
* See export option below

Texture baking:
Set the normal map’s green channel to -Y.
* This is not critical at all because if baked as +Y it can easily be fixed in UE4.

Metadata:
Blender custom properties import as UE4 asset metadata that can be read by editor scripts for automation purposes.
* See export option below


FBX Blender export and UE4 import settings:

I recommend saving an FBX export preset with these settings.

Optional:
I prefer the export settings to include only selected objects.
* It’s more efficient for me to select the specifics objects I want to export into a single FBX file prior to export, than to delete all the temp / reference / draft objects from the scene.
If you want to export Blender custom properties with to the FBX check the “Custom Properties” option

Axes:
Blender’s native model/world orientation is model’s forward facing the -Y axis, left side facing +X and of-course up facing +Z.
UE4’s native model/world orientation is model’s forward facing the +X axis, left side facing -Y and up facing +Z.
There are axis settings in Blender’s FBX export module, that theoretically, should be set like this:

However, in tests I did, The axis settings made no difference when importing to UE4, even when setting intentionally incorrect upside-down axes.
Maybe the FBX exporter writes these settings to metadata that the UE4 importer doesn’t read..
From my experience, what’s important is to orient the model correctly in Blender (see above), apply the transformations,
And in the UE4 import menu, check the “Force Front XAxis” option:

Geometry:
Make sure either “Edge” or “Face” is chosen in the “Smoothing” option to import the mesh’s smooth shading correctly ans avoid a smoothing groups warning on import:

Optional:
Depending on how much control you need over the mesh’s tangent space,
You may want to check the “Tangent Space” export option,
This will make Blender export the full tangent space to the FBX and make UE4 read it from FBX instead of generate it automatically.
* For this option to be supported, the mesh geometry must have only triangle or quad polys.
In the UE4 import settings, choose the “Import Normals and Tangents” option in “Normal Import Method”:

Armature:
Set “Armature FBXNode Type” to “Root”.
Uncheck the “Add Leaf Bones” option to avoid adding unneeded end bones.
Set bones primary axis as X, and secondary axis as -Z.

Animation:
Uncheck “All Actions” to avoid exporting actions that don’t actually belong to the skeleton.
* Un-related animations in the FBX can also corrupt the character rest pose in UE.
The “NLA Strips” option is useful for exporting a library of animations with the skeleton.
* In Blender’s NLA editor, activate the actions you want exported to the FBX.


Related:
3ds max & V-Ray to UE4 Datasmith workflow

A collection of Python snippets for 3D

If you’re interested in taking the first step into Python for 3D software,
Or simply would like to browse some script examples, your welcome to visit my Gist page,
It contains a useful library of Python code example for Blender, Maya, 3ds max and Unreal engine:
https://gist.github.com/CGLion

UE4 – Quick fix for normal map encoding

Software:
Unreal Engine 4.25 | Photoshop 2020

Quick UE normal map tip:
If you load a normal map into a UE material and the result appears inverted, i.e. holes instead of bumps or the other way:

The quick fix:

  1. In the texture settings, check the Flip Green Channel option and save it:

Annotation 2020-09-06 160838

The deep fix:
* This can be performed an automated action on multiple files

  1. Open the normal map in Photoshop
  2. In the Channels panel, select the Green channel
  3. Press Ctrl + I,
    Or Select Image > Adjustments > Invert
    To invert the green channel.
  4. Save the texture and reload into Unreal Engine.
    Annotation 2020-07-06 233156

Inverted normal map:Annotation 2020-07-06 232554

Fixed normal map:Annotation 2020-07-06 233036

Related:
UE4 Bump map
UE4 – Procedural Bump Normals

UE4 – Technical model visualization tips

Software:
Unreal Engine 4.25

This post is a summary of the tips given by Epic Games technical-artist Min Oh in his GDC 2017 lecture about improving photo-realism in product visualization, more specifically, how to render high quality surfaces.
I recommend watching the full lecture:

  1. Render sharper reflections by increasing the Cubemap resolution of reflection captures:
    Project Settings > Engine > Rendering > Reflection > Reflection Capture Resolution
    * use powers of 2 values i.e. 256, 512, 1024….
    Annotation 2020-07-06 195120
  2. Improve the accuracy of environment lighting by increasing the Cubemap resolution of the Skylight:
    * use powers of 2 values i.e. 256, 512, 1024….
    Annotation 2020-07-06 202415
  3. Improve screen space effects accuracy like screen space reflections by setting the engine to compute high precision normals for the GBuffer:
    Set Project Settings > Engine > Rendering > Optimizations > GBuffer Format to:
    High Precision Normals
    Annotation 2020-07-06 204022
  4. Use a high degree of tessellation (subdivision) for the models pre-import.
    Simpy put:
    Use high quality models.
  5. Improve the surfaces tangent space accuracy, and as a result also the shading/reflection accuracy by setting the model’s static mesh components to encode high precision tangent basis:
    Static Mesh Editor > Details > LOD 0 > Build Settings > Use High Precision Tangent basis
    Annotation 2020-07-06 210030
  6. Creating materials with rich dual specular layers by enabling material clear coat separate normal input:
    Project Settings > Engine > Rendering > Materials > Clear Coat Enable Second Normal
    Annotation 2020-07-06 211152Set the material Shading Model to Clear Coat and use a ClearCoatBottomNormal input node to add a normal map for the underlying layer:
    Annotation 2020-07-06 221027

 

Related:

  1. UE4 – Lighting calculation tips
  2. UE4 HDRI lighting
  3. UE4 – Enable DXR ray-traced reflections 

UE4 – Enable DXR Raytracing

Software:
Unreal Engine 4.25

Steps for activating DXR Ray-tracing in a UE4 project:

  1. Project Settings:
    Platforms > Windows > Targeted RHIs:
    Set Default RHI to DirectX 12
    * RHI = Rendering Hardware Interface
  2. Project Settings:
    Engine > Rendering > Ray Tracing:
    Check Ray Tracing
    * Requires restarting the editor, and may take a while to load the project afterwards..
    * I’m actually not sure if the reason for delay in re-launching the project is a full re-build of the lighting or compiling shaders..
  3. Post Process Volume > Rendering Features > Reflections:
    Set Type to: Ray Tracing
  4. Post Process Volume > Rendering Features > Ray Tracing Reflections:
    Set Max Bounces to more than 1 if needed

No DXR Reflections:
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DXR Reflections on a GTX 1070 GPU:
Annotation 2020-07-05 020433

 

Related posts:

  1. UE4 Light calculation tips
  2. UE4 HDRI lighting
  3. UE4 – Technical model quality tips

UE4 – Lighting calculation tips for Archviz

Software:
Unreal Engine 4.25

The Static Lighting calculation in UE4 is performed by the Lightmass module (UE4’s integrated GI* engine), and the result of this calculation is stored in each object’s Lightmap, an extra texture map used for storing static light and shadow information.
This post provides a list of useful tips and techniques for improving your UE4 scene setup for an efficient light calculation.

Annotation 2020-07-04 223338

Notes:

  1. The following tips are aimed at achieving a good lighting calculation/solution but they don’t include optimization methods for high performance projects.
    Namely, we don’t get into manual Lightmap UV optimizations here.
  2. The following tips don’t take into account the now real-time ray-tracing options that have become available with Nvidia Geforce RTX / DirectX DXR.

 

Scene Setup:

  1. Delete unseen polygons from your mesh, so they wont waste Lightmap resolution.
    * For example, in an interior Archviz project, delete the outer polygons of the walls.
  2. Set the architectural surfaces to cast shadows from both sides:
    Details > Lighting > Shadow Two Sided
    Annotation 2020-07-04 231158
  3. Place “light blockers” around the structure to avoid light licks.
    * Wrap the structure on all sides with scaled cubes that have an absolute black material:
    Annotation 2020-07-04 194647
  4. Set the “light blockers” to be invisible in rendering:
    Annotation 2020-07-04 194713
  5. Scale the Lightmass Importance Volume fit around the structure tightly.
    Annotation 2020-07-04 185623

 

Lightmap Resolution:

  1. Optimize the architectural surfaces (static meshes) Light map resolution.
    A higher resolution will allow the Light Map to store more detailed lighting.
    The Static Mesh resolution setting is found in:
    Static Mesh Edior > Details > General Settings > Light Map Resolution:
    * This setting can also be overriden at the actor settings by selecting the actor in the map/level and activating:
    Details > Lighting > Override Lightmap Res
    Annotation 2020-07-04 214810
  2. Use the Lightmap Density optimization display mode to inspect the actual Lightmap texel density.
    The Lightmap Density display mode also color codes the display to indicate the efficiency of the Lightmap resolution per object (green color being optimal, and warm colors being too dense)
    * Note that in many cases of Archviz you may want a higher density than the editor displays as optimal.
    Annotation 2020-07-04 195909

 

Lighmass Settings:
The Lightmass setting are found in:
World Settings > Lightmass

  1. Decrease the Volumetric Lightmap Detail Cell Size to increase the light calculation accuracy:
    * This will increase the calculation time
    Annotation 2020-07-04 214102
  2. Decrease the Indirect Lighting smoothness to get more detailed shadows:
    Annotation 2020-07-04 232028
  3. Disable Compress Lightmaps to avoid banding artifacts in the shadow gradient:
    Annotation 2020-07-04 214102b
  4. Use the Lighting Only display mode to evaluate the lighting solution:
    Annotation 2020-07-04 200645
  5. For final quality, set the Light Quality to Production:
    Build menu > Lighting Quality > Production
    Annotation 2020-07-04 222201

 

* GI – “Global Illumination” is a term referring to indirect light simulation, namely a calculation of how light reflects and bounces between surfaces.

 

Related posts:

  1. 3ds max & V-Ray to UE4 using Datasmith
  2. “Cleaning” the UE4 FPS template for Archviz
  3. UE4 – HDRI Lighting
  4. UE4 – Activate DXR ray-traced reflections

UE4 – “Cleaning up” the FPS template for an Archviz project

Software:
Unreal Engine 4.25

Annotation 2020-06-18 194857

The UE4 First Person template is a good way to start an Architectural virtual tour project, but we first need to “clean” it up, namely, get rid of all the unnecessary objects and settings.

Start with the obvious:
Delete all the cubes and blocks. (Simply select them and press delete)
The quickest way to select all these objects is through the World Outliner window.
Select all the unneeded objects (see image below) and delete them.
Note:
I’m intentionally keeping the 4 surrounding wall objects because I want them to serve as invisible barrier objects that will stop the player from wondering of the platform.Annotation 2020-06-18 195553

So now our level looks like this, with weird static shadows left by the “BigWall” objects that were deleted.
It’s not really critical to fix this at this stage, but if you want to get rid of the weird left-over shadows, simply press the Build button to re-build the lighting, and they will be gone.Annotation 2020-06-18 200303

Making the walls invisible:
Select the 4 wall objects, and in the Details window, in the Lighting Settings uncheck Cast Shadow,
And under Rendering uncheck Visible.
The level is now clear, and when we press play, we can free roam on the empty stage until we hit the invisible walls.
* You can re-build the lighting to get rid of the walls static shadow.
Annotation 2020-06-18 203043

Time to get dirty!
We now have to get rid if the FPS rifle and shooting setup….
Select the FirstPersonCharacter actor, and in the World Outliner window click Edit FirstPersonCharacter to open the actors Blueprint:
Annotation 2020-06-18 210611
In the FirstPersonCharacter Blueprint, navigate to the Viewport tab so you’l be able to see the mesh components clearly,
And in the actor Components Window on the left, select all the unneeded components, delete them and press the Compile button.
* make sure you don’t select the FirstPersonCamera or any of the inherited componentsAnnotation 2020-06-18 211326
A list of reported errors will now be displayed in the Compile Results window, because we deleted objects that are referenced by the Blueprint, we will fix this in the next step:Annotation 2020-06-18 211509
Navigate to the Construction Script tab, Select the AttachComponentToComponent node (currently displaying an error) and delete it.Annotation 2020-06-18 213100
Navigate to the Event Graph tab, locate the first Event Graph at the top of the Blueprint, this is the Event BeginPlay graph.
Select the 2 Set Hidden in Game nodes (currently displaying an errors) and delete them:Annotation 2020-06-18 213152
Locate the Spawn projectile node graph at the bottom of the Event Graph,
Select this whole section, delete it and press Compile.
Annotation 2020-06-18 213243
The Event Graph should now look like this, and compilation should be without errors because we deleted all the Blueprint parts that were referencing the deleted actor components:Annotation 2020-06-18 213349

Almost there..
It’s time to remove the small red targeting cross-hair icon displayed on the screen when playing.
The cross-hair icon is defined in the level’s HUD (Heads Up Display) Blueprint class.
The easiest way to remove it is to simply remove the HUD class from the level.

Note:
The FirstPersonHUD class can be useful to an Archviz project for displaying branding and architectural data on screen so it’s good to keep it in the project. it can later be modified to suit our needs used again (doing that is beyond the scope of this article).
If you wish to edit the HUD Blueprint instead of disconnecting it from the level, you’ll find it in Content > FirstPersonBP > Blueprints > FirstPersonHUD:
Annotation 2020-06-18 220637

To remove the HUD from the level, navigate to the World Settings window,
If it isn’t displayed open it from Settings > World Settings:
Annotation 2020-06-18 220538
In the World Settings window, under Game Mode > Selected GameMode, open the HUD Class drop-down and instead of FirstPersonHUD, choose None.
This will remove the HUD from the level but wont delete it from the project:
Annotation 2020-06-18 220513

Were done!

You can now decide whether to keep the default daylight setup or maybe delete its actors and create an HDRI lighting instead,
And you can now import your Archviz scene via the Datasmith plugin.

Hope you found this article useful! 🙂

Related posts:

  1. 3ds max & V-Ray to UE4 Data Smith workflow
  2. UE4 HDRI lighting
  3. UE4 – Connecting the directional light to the atmosphere
  4. UE4 Architectural glazing material
  5. UE4 – Archviz Light calculaion tips

 

UE4 – HDRI Environment & Lighting

Software:
Unreal Engine 4.25

Annotation 2020-05-20 162811

Creating HDRI environment backgruond and lighting* in UE4:
Note:
Lighting using a panoramic HDRI background is also referred to as IBL – Image Based Lighting.

* The example HDRIs in this post are from www.hdrihaven.com

  1. Import HDRI environment file.
    Note:
    The file must be saved as a *.hdr file and not *.exr because AFAIK that’s the only way UE4 will recognize it as an HDRI environment and encode it as a Texture Cube (cube map)
  2. Enable the HDRIBackdrop plugin:
    Go to Edit > Plugins
    Type “HDRI” in the search field to locate HDRIBackdrop and enable it.
    * You’l have to restart the UE Editor before using the plugin
    Annotation 2020-05-20 153925
  3. Drag a Lights > HDRI Backdrop object to your level:
    Annotation 2020-05-20 154657
  4. In the HDRIBackdrop details, select the wanted Cubemap:
    Annotation 2020-05-20 155212
  5. > Set the HDRIBackdrop‘s Intensity (self explanatory..).
    > Rotate the HDRIBackdrop around its Z axis to set the environment’s direction.
    > Set the HDRIBackdrop‘s Size.
    * Make it larger than your whole scene,
    And if Use Camera Projection is unchecked make it also large enough so that noticeable objects in the HDRI image will be distant enough as to not move incorrectly when you strife.
    * When Use Camera Projection is activated the Size property has no effect.
    > If Use Camera Projection is unchecked, set the Projection Center Z value to define the background image height below which it is projected as a flat ground.
    > Lighting Distance Factor defines ground projection area that will appear to receive shadows from your scene objects.
    * Set this attribute to 0 in-order to turn off the ground projection shadow.
    > Use Camera Projection:
    Activate this option to get a traditional infinitely far background with no flat ground surface projection.Annotation 2020-05-20 160338

 

Related:

  1. Sun & Sky link
  2. UE4 Architectural Glazing
  3. 3ds max & V-Ray to UE4 Datasmith workflow
  4. Preparing an FPS project for archviz
  5. UE4 – Archviz Light calculaion tips

3ds max & V-Ray to UE4 – Datasmith workflow basics and tips

Software:
3ds max 2020 | V-Ray Next | Unreal Engine 4.25

This post details basic steps and tips for exporting models from 3ds max & V-Ray to Unreal Engine using the Datasmith plugin.
The Datasmith plugin from Epic Games is revolutionary in the relatively painless workflow it enables for exporting 3ds max & V-Ray architectural scenes into Unreal Engine.
Bear in mind however, that Datasmith‘s streamlined workflow can’t always free us from the need to meticulously prepare models as game assets by the book (UV unwrapping, texture baking, mesh and material unifying etc.) (especially if we need very high game performance).
That being said, the Datasmith plugin has definitely revolutionized the process of importing assets into Unreal, making it mush more convenient and accessible.

 

Preparation:
Download and Install the Datasmith exporter plugin compatible with your modeling software and Unreal Engine version:
https://www.unrealengine.com/en-US/datasmith/plugins

 

In 3ds max & V-Ray:

  1. Make sure all materials are VRayMtl type (these get interpreted relatively accurately by Datasmith)
  2. Make sure all material textures are properly located so the Datasmith exporter ill be able to export them properly.
  3. In Rendering > Exposure Control:
    Make sure Exposure control is disabled.
    Explanation:
    If the Exposure Control will be active it will be exported to the Datasmith file, and when imported to Your Unreal Level/Map a “Global_Exposure” actor will be created with the same exposure settings.
    Sounds good, right? So what’s the problem?
    The problem with this is that these exposure setting will usually be compatible with photo-metric light sources like a VRaySun for example, but when imported to Unreal, the VRaySun does not keep its photo-metric intensity. (in my tests it got 10lx intensity on import). the result is that the imported exposure settings cause the level to be displayed completely dark.
    Of-course you can simply delete the “Global_Exposure” actor after import, but honestly, I always forget its there, and start looking for a reason why would everything be black for no apparent reason…
    * If your familiar with photo-metric units, you can set the VRaySun to its correct intensity of about 100000lx, and also adjust other light sources intensity to be compatible with the exposure setting.
  4. Annotation 2020-05-12 192439
  5. Select all of the models objects intended for export,
    And File > Export > Export Selected:
    * If you choose File > Export > Export you’l still have an option to export only selected objects..
    Annotation 2020-05-12 192506
  6. In the File Export window,
    Select the export location, name the exported file,
    And in the File type drop-down select Unreal Datasmith:
    Annotation 2020-05-12 192550
  7. In the Datasmith Export Options dialog,
    Set export options, and click OK.
    * Here you select whether to export only selected object or all objects (again)
    Annotation 2020-05-12 192654
  8. Depending on the way you prepared your model,
    You may get warning messages after the export has finished:
    Explanation:
    Traditionally, models intended for use in a game engine should be very carefully prepared with completely unwrapped texture UV coordinates and no overlapping or redundant geometry UV space.
    Data-smith allows for a significantly forgiving and streamlined (and friendly) workflow but still warns for problem it locates.
    In many cases these warnings will not have an actual effect (especially if Lightmap UV’s are generated by Unreal on import), but take into account that if you do encounter material/lighting issues down the road, these warnings may be related.
    Annotation 2020-05-12 192730
  9. Note that the Datasmith exporter created both a Datasmith (*.udatasmith) file, and a corresponding folder containing assets.
    It’s important to keep both these items in their relative locations:
    Annotation 2020-05-12 204541

 

In Unreal Editor:

  1. Go to Edit > Plugins to open the Plugins Manager:
    Annotation 2020-05-12 192802
  2. In the Plugins Manager search field, type “Datasmith” to find the Datasmith Importer plugin in the list, and make sure Enabled checked for it.
    * Depending on the project template you started with, it may already be enabled.
    * If the plugin wasn’t enabled, the Unreal Editor will prompt you to restart it.
    Annotation 2020-05-12 192901
  3. In the Unreal project Content, create a folder to which the now assets will be imported:
    * You can also do this later in the import stage
    Annotation 2020-05-12 193030
  4. In the main toolbar, Click the Datasmith button to import your model:
    Annotation 2020-05-12 193043
  5. Locate the the *.udatasmith file you exported earlier, double click it or select it and press Open:
    Annotation 2020-05-12 193129
  6. In the Choose Location… dialog that opens,
    Select the folder to which you want to import the assets:
    * If you didn’t create a folder prior to this stage you can right click and create one now.
    Annotation 2020-05-12 193301
  7. The Datasmith Import Options dialog lets you set import options:
    * This can be a good time to raise the Lightmap resolution for the models if needed.
    Annotation 2020-05-12 193326
  8. Wait for the new imported shaders (materials) to compile..
    Annotation 2020-05-12 193408
  9. The new assets will automatically be placed into the active Map\Level in the Editor.
    All of the imported actors will be automatically parented to an empty actor names the same as the imported Datasmith file.
    In the Outliner window, locate the imported parent actor, and transform it in-order to transform all of the imported assets together:
    * If your map’s display turns completely dark or otherwise weird on import, locate the “Global_Exposure” actor that was imported and delete (you can of-course set new exposure setting or adjust the light settings to be compatible)
    Annotation 2020-05-12 193517

 

 

Related:

  1. Preparing an FPS project for archviz
  2. Unreal – Architectural glass material
  3. Unreal – Camera animation
  4. UE4 – Archviz Light calculaion tips

UE4 – Creating two sided material effects using the TwoSidedSign node

Software:
Unreal Engine 4.24

The TeoSidedSign node let’s the shader “know” if a rendered polygon is facing the camera or not by outputting a value of 1 for facing polys and -1 for back-facing polys.
This is useful for creating materials that have different properties when seen front-facing or back-facing.

Example 1:
Blending two different colors based on face direction:

  1. Check the Two Sided material attribute.
    * Needed so that the engine will render the polygons beck sides.
  2. In the material blueprint, create a blend of to colors using a Lerp (LinearInterpolate) node and connect it to the material’s Base Color input.
  3. Add a TwoSidedSign node to get polygon facing input (1,-1).
  4. Connect the TwoSidedSign node’s output to a Clamp node to clamp the values to (1,0).
  5. Connect the  Clamp node’s output to the Lerp node’s Alpha input so that the polygon’s facing direction will control the Lerp blend.

Note:
You can use this method to blend any other material attribute based on polygon facing direction.

Annotation 2020-05-11 133226

 

Example 2:
Create an “inwards facing” flipped normal material:

  1. Set the material’s Blend Mode to Masked.
    * Needed for being able to make areas parts of the mesh invisible.
  2. Check the Two Sided material attribute.
    * Needed so that the engine will render the polygons beck sides.
  3. Add a TwoSidedSign node to get polygon facing input (1,-1).
  4. Connect the TwoSidedSign node’s output to a Clamp node to clamp the values to (1,0).
  5. Connect the Clamp node’s output to a 1-X node to invert the facing input.
  6. Connect the 1-X node’s output to the material’s Opacity Mask input so that polygons facing the camera will be invisible.

Annotation 2020-05-11 130703

 

Related:

  1. Blending material using Paint
  2. Material Functions
  3. UE4 Bump Map